<style>
  aside.article h1#title {
    color: red;
  }
  #article h1.title {
    color: skyblue;
  }
</style>

<aside id="article" class="article">
  <h1 id="title" class="title">
    Lorem ipsum dolor sit amet consectetur adipisicing elit. Enim, voluptate.
  </h1>
</aside>
